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GRSM_CT_FIRE_DEBRIS_VOLUME_15_36 (FeatureServer)

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Service Description: GRSM_CT_FIRE_DEBRIS_VOLUME_15_36

Service ItemId: 7dfb90a9868c409b967cc2da6e38f918

Has Versioned Data: false

Max Record Count: 1000

Supported query Formats: JSON

Supports applyEdits with GlobalIds: False

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Description: Estimates of the potential volume of debris flow (in m3). These predictions are made at the scale of the drainage basin, and at the scale of the individual stream segment. Estimates of probability, volume, and combined hazard are based upon a design storm with a peak 15-minute rainfall intensity of 36 millimeters per hour (mm/h). The preliminary hazard assessment relies upon empirical models to estimate the likelihood and volume of debris flows for selected basins in response to a design storm. Beginning in 2016, the empirical models are based upon historical debris-flow occurrence and magnitude data, rainfall storm conditions, terrain and soils information, and burn-severity data from recently burned areas. Post-fire debris-flow likelihood, volume, and combined hazards are estimated at both the drainage-basin scale and in a spatially distributed manner along the drainage network within each basin. The characteristics of basins affected by the fire were calculated using a geographic information system (GIS). Debris-flow likelihood and volume were estimated for each basin outlet as well as along the upstream drainage networks (pixels where the contributing area is greater than or equal to 0.02 km2). Independent variable values were calculated for each pixel along the drainage network and summarized at the stream segment scale to obtain estimates of debris-flow likelihood and volume. Debris-flow volumes both at the basin outlet and along the drainage network are predicted using a multiple linear regression model (Gartner and others, 2014). The multiple linear regression models are used to estimate the volume (V, in m3) of material that could issue from a point along the drainage network in response to a storm of a given rainfall intensity. Potential debris-flow volume is calculated with equation 4: (3) ln(V) = 2.89 + (0.17 × sqrt(ElevRange)) + (0.3 × ln(HMkm)) + (0.47 × sqrt(i15)) Where • ElevRange is the range (maximum elevation–minimum elevation) of elevation values within the upstream watershed (in meters), • HMkm is the area upstream of the calculation point that was burned at high or moderate severity (in km2), and • i15 is the spatially-averaged peak 15-min rainfall intensity for the design storm in the upstream watershed (in mm/h). Volume estimates were classified in order of magnitude scale ranges 0–1,000 m3; 1,000–10,000 m3; 10,000–100,000 m3; and greater than 100,000 m3 for cartographic display.

Copyright Text: USGS

Spatial Reference: 26917 (26917)

Initial Extent:
Full Extent:
Units: esriMeters

Child Resources:   Info

Supported Operations:   Query   Create Replica